A primary rationale for the development of alcoholism typologies, and for the identification of alcoholism vulnerability alleles, is to reduce heterogeneity and to provide individualized and effective treatment. Because the serotonin and dopamine neurotransmitter systems have been implicated in the etiology of alcoholism, as well as being systems modifiable by pharmacological agents, they are logical systems on which to focus with respect to treatment outcome. This collaborative project, to be conducted jointly by the applicant and a clinical psychologist, has the following specific aims: (1) to assess whether particular genotypes have an effect on treatment outcome; (2) to assess whether the effect of genotype on treatment outcome is mediated by temperament, specifically in areas having to do with impulsivity, apprehensiveness and social sensitivity; (3) to evaluate possible differences in treatment outcome for individuals assigned to empirically generated subtypes; (4) to evaluate potential associations between alcoholism typology and genotype. A minimum of 300 participants (62 percent men) will be recruited as consecutive admissions to an outpatient treatment center. On intake, participants will self-administer a questionnaire battery assessing alcohol use and the HA, NS and RD temperament dimensions, and will donate 7ml of blood for genetic analysis. Following the intake assessment, a six month follow-up interview will assess alcohol and drug consumption patterns to evaluate treatment efficacy. We will assay genetic markers that are candidates for associations with either temperament and/or with alcoholism: serotonin transporter (5HTTLPR), serotonin 2c receptor (HTR2C), monoamine oxidase A (MAOA) and dopamine receptor D4 (DRD4). Results of this research will be a first step in increasing our understanding of the associations among neurotransmitter systems, alcoholism typology and treatment outcome.